protobuf3: support cross compilation

PR #48450

pkgs/development/libraries/protobuf/generic-v3.nix

@@ -1,11 +1,12 @@
 { stdenv
 , fetchFromGitHub
-, autoreconfHook, zlib, gmock
+, autoreconfHook, zlib, gmock, which, buildPackages
 , version, sha256
 , ...
 }:
 
-stdenv.mkDerivation rec {
+let
+mkProtobufDerivation = buildProtobuf: stdenv: stdenv.mkDerivation rec {
   name = "protobuf-${version}";
 
   # make sure you test also -A pythonPackages.protobuf
@@ -28,8 +29,10 @@ stdenv.mkDerivation rec {
       --replace 'tmpnam(b)' '"'$TMPDIR'/foo"'
   '';
 
-  nativeBuildInputs = [ autoreconfHook ];
+  nativeBuildInputs = [ autoreconfHook buildPackages.which buildPackages.stdenv.cc buildProtobuf ];
+
   buildInputs = [ zlib ];
+  configureFlags = if buildProtobuf == null then [] else [ "--with-protoc=${buildProtobuf}/bin/protoc" ];
 
   enableParallelBuilding = true;
 
@@ -54,4 +57,7 @@ stdenv.mkDerivation rec {
   };
 
   passthru.version = version;
-}
+};
+in mkProtobufDerivation(if (stdenv.buildPlatform != stdenv.hostPlatform)
+                        then (mkProtobufDerivation null buildPackages.stdenv)
+                        else null) stdenv